SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fa3b88f41fd203d10d13d359add78f34d6e08d1a988b46bfe96b272d4526416' 
  AND token = '6bf5wBSTNvKMfXcb2Qg42LpAR7S7GC+cVxYs/ZakknE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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