SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eeaf577215210dd722d9d79d2d47065023e3af2bc728d00c289eb125901af545' 
  AND token = 'R1MnBuNNUyDdHNmSUEctPltXLkQOqq/PGxLCRoKba7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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