SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a433fcaad269757c22bb2143df808e96286f2409be1b9ed9c7455e0f4b8e0053' 
  AND token = '6d9dIyGbNDVXI/bBIITFAmvxLL6UfxVAPDyXO1AYhuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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