SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e89d339cff278bb0d73e4a47a7107dc696f9d1cf22712ba8402be20615b418fa' 
  AND token = 'DcLf8nY8p+7hEePiJfIy/aij2UzGXsnRXOUzQGLdHk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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