SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d34aad23256eea1fa52d789ba1a3910a261d8244421bd30a0de511615698d0' 
  AND token = '+T7KJf5t3ScAhzHvG5YTrdP0yCOIMPtx6HNRE3seju4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}