SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd3a985f15536d02883677af37ecbc0315fe334357fadeca8b2c6d008c718f710' 
  AND token = 'RFiStEJCfnVfO6o3izycDuUHmbG22virV0xC6mt2l54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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