SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cb63fb7b03910ccd56db0ac1be881b014131231ca901e4d8019b64eb9d7e874' 
  AND token = '39iNMuYrTt0MkxD4xQ+nU8ydNSJfVieQTLQIr8/9nws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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