SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '846474a693a6972a5e2184917562d884854c9b2fc9a7d8e8daeddf2044883339' 
  AND token = 'M9KiO7eCajtBgdfcqjwqS4YPT4ULkcFfV47Kq2QoXCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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