SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfaf9a47a522d7e14edb6c17f36942c6ebfb457f5a368fdb5c3fc935de4a82f3' 
  AND token = '+srgjO5G8TYELkyJyBxWZJWHocVhOGLrQMUakCscHtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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