SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd9d261c44a5e072bfb2bfa1726a98c09d1555be13c301a0e8474f9a51fdd0803' 
  AND token = '7qk6Dg7c7CYchNUccE4B7100UhsPo35uFspXozjWfCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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