SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2819d76aea0bbfe9f4348dcdf322f40a59537fefb215af38a64c1ce9daf7516f' 
  AND token = 'wzWerOWiMxe+R38fsuyBv/MxqpKU9Xm4t/xikX9gKB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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