SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a36ecebc62ddc56819686778f5aa482266bb974e695b4fae0a0a55b27dfdff9b' 
  AND token = 'nzfcWYMPSDojFJZy2WidJSKbnL+sASf7hUitQJznu2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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