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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c4b299bc35061159519d3a279ae7f5e8d7b644f6a9fb278ddf98ffa23cf1e78' 
  AND token = 'r/8SCIaigvV5QAPMhgiDbEhn4dZ/CasD/rM/p8WJoYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}