SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b123da6c95f459581e526e420f264f2ec201432578dd768e89c06846be24b2ac' 
  AND token = 'zoSr5pRQY0nR5uMm2GDlHP5lSCnM6xPJmTo2cIKT80s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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