SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c1af11ce42058eb98026a93d0c615f6e85489fc341cd2f81e6fe904344d5738f' 
  AND token = 'r6HFvzUDqvKDa8ptCegU+ZIAKNyAlg2Zpw+L38hiW4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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