SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5eb1f74f94c9311a311c5897463134dadfac88872ecd85d5f91af81754513eda' 
  AND token = 'RHGCk+WeLcWYlnGdUOS2f7/fTa6OX6FVYw3z2kbapPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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