SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f2d76995515f6364b0678629b8cd8611b02c6c2cf2ae1a02f25a71a36344e786' 
  AND token = 'qNpAB6bLtMBj0gzGD6sX+cszBlv/AKp0zFaG2BYkjbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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