SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f29d0239e186ed3499e4771264fc3cc84f6ced85857b180af08d4e54b14f6df0' 
  AND token = 'nHJjJpY01ofSCwMTlVDyRC+fmHyPHiCglA+n9OctApg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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