SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '689653a3396ee153bda68bcf817652e7ca92e65a254f6400549fa4b924abbb55' 
  AND token = 'SsiAt9TtAsuKSvFxINmIhyy86ICttCgb39ZTt+2Zm50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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