SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'f44abdb1521ee606c7e169b24cb9bed4acc1d8f351b449a70439e251eecd2d87' 
  AND token = '8adaVId4wLCtyPyMmI1orEN+TDNqt97SYcCVIcFTNfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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