SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16abbd175646652b2353f9ed58e18c81ad3e6b90afb83a842f209f5fe313b575' 
  AND token = 'mXwlnak4/x3lfqsq3VRxjl/nJQgBFnJaHICWxdqDnNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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