SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7267269cf33492eddf1e0ef32726505d83621fd9d0429423414c70e0b949d98' 
  AND token = 'tFV/IsGcnNSKNUJouGV9qrkRJQ+ZGOzFnT4n+iMHvv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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