SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1bc94bb0deb96f2f6a42b96578919d0651a4a1b92cbb50d749c14e47612dbab2' 
  AND token = 'pznME8OVU65d4oqOpJ7FMI6Ag9mbACDFlq/1QpguQIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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