SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3778305b7df23bc4175c88151557812c943f61e6ea69368a2710190cbebcaca1' 
  AND token = 'ZvXi7w6KhDQm7R+8GTFwOI0CLJJMlQzgUW/G2KnuETs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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