SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47ac370f0f9377c2242c52c2d78dd4d0f15b1f2a933d60e4bbe9eafcf24d8f84' 
  AND token = '9yqxHufd2xV+x/U7bl2JIe0YuSIsWI9htMbkEd9SLnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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