SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab979098143a26ce9db224038985fbca0057f9d85847f0d5c19e68957e7b1a4' 
  AND token = 'TvjqPNTWzkm17RUBpMG+xVFql3HTWZTMtvNQgCjV9LE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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