SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6af67ca0f23636f9d3b277e3d17afcde13a5800c52da007514d0e0ff14894d5f' 
  AND token = 'lu+hqaCurWVqKZ5ToJWcxu4xQEWK2jO0szGng+YHdr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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