SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d66c8f164a4de5d0843aee6cd2565a69794f89644098e69c404553787a320f3' 
  AND token = 'X94GYLnWmNVuxb0ZMAWG0osOz4X/ow++blFUHifhgvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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