SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '471e7014576bb15f443f0884cd6f0e101fd13ace75588c0dc6eb8c195ca95b4a' 
  AND token = '2xKb9hGpk1Ul7BLSgRaBzIV/JGwyP8xiRSrOyh4YZbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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