SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a332d97eea456bc119662c9172a32691b9d0a83b246dcf9a609308b15aff15e7' 
  AND token = 'VDYsMItFg+N4MllPlv5XOrKhXRkyGryz/WW1rcbfQj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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