SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9735ab532f3bd73334867fcf1ce0ffda6294c7b50df52a0f8fb994b149e656f' 
  AND token = '1/Mk3OzGLYKkoQZto3yVhKY+u6TWhyj5sSpBo6nqR9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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