SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '975e625ac54ad869be5381e1b8dce9d67641e3bc68225ac05f12c4cc6a32006b' 
  AND token = 'JjdmIYgtsofteOXevC02PysFjwnon+EnYqh11PxNaFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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