SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f064b47be49fc4c0900310217940fe445eb8a53f45dbcdc21c03b174a0fefe9d' 
  AND token = 'cvkcy46gYVCsZG4YrrmozKKn/pZugrFghEBwKXL2Re0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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