SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fbdbaf431162bff56c5f4d07f3190be6df2273bfd379862b02d22cda9837b7' 
  AND token = 'jJJCq8lgrdl/0bSjpK8tXkmzhqSmBRE2yfSw4DH4+W4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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