SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0a74ce835124e64480579d6635f34260e7d47c8114b5eafdc9b82e59f38b741' 
  AND token = 'BQ5NdDV0cGPQ4SS0PBKsgIOWZN7okkL8Xu9x0eWBnHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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