SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b577dce6108911bcfc1c36a2508264c64f17fa643a9a56bc5932497a65d31013' 
  AND token = '687MavBjEUocLeLGGDNk3CgcSqziO7lGVLIYphwwEZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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