SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1512adbd7ee5625c42d86ff5f7991fa67018ff948e51910278cfd82bdc6590bd' 
  AND token = 'NM/JfdN2JlSM5raLeGeV0dkIib7FOHRQlWERXSYRJ8s=' 
  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"
    }
  }
}