SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756ed88d1cbbb1c45678d8d650ecf72e4228b506e10a48576def7147042fa159' 
  AND token = 'cqjhyOhrCmagFPS6idm3obi3cyzaFQrrWQTVYCRk9oQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}