SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ffa9cb669d62eea4044c1b5273c6f439b807fdf518b32613ad99458a5a6a995' 
  AND token = '7KxUu6NXsgmdVAgjiQUqw2oDXdYgBxbdObosaKVQFUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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