SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f17ff7999b9ad64e5c7bbd0c58321129553d6a8a1d22835926f80585fa6c08cd' 
  AND token = 'rZJtctBMmd4GqwsnyzWpuCmtH2hj921GTSttY2Brt2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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