SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76183229a69380fb35649e70b8921049c2b717443cda141044088f498b5cfaae' 
  AND token = 'KpDuvLxhku3T8vMjL1ayUvbQD91Oqn2nGpap65HKIgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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