SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9ec36fe2bcd19aab33efbcba19020e83c46bf4d29cfd317d55cc7a751ad6b82' 
  AND token = '5fEC9BTT2ZsOXaVM+6ckFQuvkcAeIWMi49qlbzLTTUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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