SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a79727b38b53515d09069d53b5922a523c9a162935ac06e71715c67a4ea94674' 
  AND token = 'P7SReYoZEovGC1F6Ld2Z/+OWBphJJ5qEUTufHjitl2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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