SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a8c91d0d006b4fbadf90fda5c5ed64685f332dc932a84f2eb058161d1efbff' 
  AND token = 'ul5yc3hfgHf0XfKW1Uud2FoFdH3ssCVRjs1Slv9Wyf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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