SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e390ff81ab5525ec1817855fce870faa883d61bc8e50a3dcdc03b9cb0164c47a' 
  AND token = 'iwK7+ObIrCgxN7UCTge8HmYjPmhZv2xBv4nyijA+XSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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