SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4358b0304d9d4a6f5f47004c64539289b554e5cdba466632e72b4185c4bcf949' 
  AND token = 'E/isY5yBpaCcDln4xkRsBc2m//0ifK1n9D50MxXpyOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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