SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6dcae09047cdaac89aef489fb21269bb1eedd1410e19339473f2dfa1e312aba' 
  AND token = '+9f2dHtzh9knoj5JDgev06c104cUB/zcJFYDACI5cMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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