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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3a485912a943bcfc1ced843c0dc6a4c988c4b6d4c227928bb6620d7a3bcb49' 
  AND token = 'yIFjIkP4XzjdFmtcNdBVvUxzzv+BjjoPEMP2xDoybs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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