SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f9a3437af79975308a2a7055dc272ff7e4063401000ec70be2679b4a4c72b5e' 
  AND token = 'c8zGLR74OZFz4PprQkvqHDgji+7M/IDxGwgRB7JWCWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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