SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3ec6cb1addbd2142b1a1f33abbf9d673649a1b4d8b81e19bbff77c6b7215bac' 
  AND token = 'P7pjoamTBU+RDMMyLUUtXpTIsEev1geZgLV4UttMRNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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