SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b91c56958418f057d28034ec869d0814d8f8761e42a8b5bf563b9e23968f8c5' 
  AND token = 'NUOfa3QWbVHPzlLz3mV1hXv3BFN6QEpEfGgfFwRY088=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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