SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '582764afee8319f6f03d18ecb7bbfb4bac1ed28d29409cf723531e7773b2e29a' 
  AND token = '1fD2r+QwiXOJndw+b2KBiPTyQKJYUIplZTV1hevfztg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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