SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3100d5a380c1a3ff0871f897d921bd31c76bd58c0e2bf270fc5c57d43e1933d8' 
  AND token = '3w3k6hpk3w4dKqhsaAXJ1JweOLF1NpTdsUqB+Gm+TQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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