SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8c49303b0997419e9005d6d017fdc4dd4cfa750aa3de985450fd34aabeef93e' 
  AND token = 'PGsyRXhzXqxRjBkBlakyw3yy4V5omOCqfCGoJdr3/bI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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