SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3fe03e90861acf590497e05ca122153b7743011339ec332123d90b6e88123692' 
  AND token = 'DVykNAmlbY+hsl4O1EPX75C+3JYNotbRB9cEhbew1cg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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