SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8e556f75c773add7ff75568d0d0f5dcf0f1e81743c4f2a647985148ab107286' 
  AND token = '9sA5E7S303OnNuTJdfD8baPW6N295CRW86HA676JIe8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}