SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c121535e19838167aa7bcd91692cca9e300667fda58147975b0b07d61d42b52' 
  AND token = 'TdZdh9a7u8hSSPaAjTgNcRDXUEpxcuDDJmcvB7IPCqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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