SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8ffe61420e50a43a389708082925d3d959ff3b22c7f8d364844b24af1de3782' 
  AND token = 'BZsmz8knmz7gJZWmpM63HOGeS41AB5Tm3pV5RCw+cEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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