SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e48592114631a433baf681139576c2e50769d9cbd355b3cbd8585c2c20aebd30' 
  AND token = 'N5uDKQ4G0ynBiVYWE+QyuJqq42L4ZT6ruDo/mZlPiW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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