SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5aff8c8d1bc31ac8a118c8c04f9b5848a0ad4e578fac27976b3d3fa1f9875bb' 
  AND token = 'Y8gJXrV30TbnnuUAuqHS/LhY1rIzlyOU4tZiwG6JkNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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