SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdf5c7e2cd1940b8486dc0e1787562626aa3964c1220c4ac5984591afac22f77' 
  AND token = 'URTdkZLhqcpD/JKsEYZJZBISpZh7+1mMZqq0Z+jNdwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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