SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6aecc68ba139fe51dbb9c3aab69245468df5acbf0f0b17eeb0c60e093fb26eaa' 
  AND token = '3wUKYLd0QwZ1DrBDNeLPTDFXYP3cgJUBj5ngFrRqGb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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