SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79bffef188528dad08c304cac766da0ad6862fd90187da6429ab703f3702d0b3' 
  AND token = 'pgLGhRK3bp3yWlsOoo+399LtXsZJ9L5Ok6ThtUIUxVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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