SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4bdd4795664c0b8a80657e3ad06fb7644bc62fc5f4abb79dd9f83d0fe15ab91' 
  AND token = '+gb4wJ89qZXoBCyJ+aC++XzzGmvT2y+p/Jcmflbk+/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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