SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3903169362027880a51e77536356dae0f6d6f57b2c48386c7286bde0d783faa' 
  AND token = 'uslQFfRi2tKw9TNM7zzdYKwi5M2ZFtFaIucSkgIuYrs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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