SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42a74525351afea50add850dac6dd0b811e79406139a030d258638aa3e14aa62' 
  AND token = 'AsN1HXEvbGeBIA1UI8InKYtdjebN3YBj3GM2xXM9czQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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