SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7eef430217c86cc691b016617d24a30cd0000da493805e3525db299ee91be88' 
  AND token = 'uw/Vm1W/Asa7rMV1iCtYyQAWb9fqz0b/Nx/ZzzOwE28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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