SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968df4e62387d7d5ddb41ba67cd351595400497ee6b235e74997583fa9627d49' 
  AND token = '6f2jsPd+Xz4i/GW3AFuVzAFmIsl93jqUNqFd4emUZ7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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