SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3199d7c2d50299e0016445eee7e850fbb7f28b44e9becc75f5ecc0195b645a49' 
  AND token = '2gDOsaGTh5Sv3LpixkYYRcte9qqBUWT/E4W34fSUnI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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