SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '65db60605c427c6fdd2fa10c249a523a852e73eae2a93ca0dd54bc0f30678d1a' 
  AND token = '3GR3Oaf8GkUadXBk3KFt2WPHj9L9GxFojEp0y/SBLKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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