SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c023ad76c0b5c9d63ae82d420f83a0789b6e3f90c437ddbf031d339fa9e2def7' 
  AND token = 'gtOaqTElhhavl24YB/sztEyLUCKMYlGH/WXP+Zj++lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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